Fusion Tdci Zetec Heated Rear Screen Fault

I have a Fusion 55reg TDCi Zetec Diesel, I have a small fault which is the Heated Rear Screen will not work. When the Heated Rear Screen Switch is pushed it will illuminate but it will not turn off automatically just stays on, and the rear screen does not demist and work, I am not sure if door mirrors are heating. I have checked the Heated Rear Screen fuse F32 at 7.5A and this has 12v on both sides when the switch is pushed. Does anybody know the colour of the wires to the Heated Rear Screen or have any other idea's. Thanks in Advance